In the wake of their bitter split from the AFL-CIO, three unions representing 4 million workers can no longer coordinate their lobbying efforts with those of the federation.

Officials with the labor umbrella group said the Service Employees International Union, the International Brotherhood of Teamsters and the United Food and Commercial Workers are no longer welcome at federation meetings to plot lobbying strategy after they left the federation last month.

“These unions have dropped out of the AFL-CIO, and we have to have our own program,” said Chuck Loveless, director of legislation for the government worker union AFSCME, a federation member. “This is a decision they’ve made.”

Bill Samuel, the AFL-CIO’s top lobbyist added: “The break is clean. It has to be that way according to our constitution and according to democratic principles. After all, we’re a membership organization.”

The development comes as Democrats on and off Capitol Hill try to assess the impact the labor breach will have on the party’s fortunes.

The federation’s political program, already hobbled this year by simmering tensions with the breakaway unions, is widely considered weakened by the split. Less clear, however, is its effect on labor’s clout in Congress.

Labor officials argue their lobbying operation will continue to be a force, but they acknowledge the split will cost their efforts some efficiency. Samuel said even on those issues where both camps agree, when they develop strategies separately, they “may be working at cross-purposes. But I’d hope to be able to avoid that.”

The breakaway unions are set to meet next month to formalize their new federation, called the Change to Win Coalition.

Despite the separate structure, lobbyists with the dissident group are aiming to collaborate with the AFL-CIO. “Our hope and expectation is to continue to work closely with the AFL-CIO and the affiliated unions on our shared legislative goals as we always have,” SEIU spokeswoman Avril Smith said.

Escalating strains over union efforts in the states may make that difficult. The SEIU is clashing with AFSCME in California as it drives to recruit home health-care workers away from the government workers union.

“Where unions are at each other’s throats, they’re going to be less likely to work together,” an AFL-CIO official said.

On big-ticket issues, unions from both camps will continue membership in broader coalitions, which means they will be working side by side this fall to oppose new tax cuts and cuts to Medicare, among other items.

Labor insiders, hopeful the split will not spell diminished lobbying power, point to labor’s strong but unsuccessful effort to defeat the Central American Free Trade Agreement last month.

In the very midst of the federation rupture, lobbyists from both camps mounted a unified campaign to scuttle the trade pact, lining up all but 15 House Democrats against it.

Their drive helped force the White House and the business community to extend the timetable for the vote on the measure and exert heavy pressure on wavering lawmakers to secure a razor-thin victory.

But labor’s campaign against CAFTA had been ongoing for months and was unlikely to be derailed at the final moment by the shakeup.

Now, when the AFL-CIO’s army of about 60 lobbyists huddle on Monday mornings to discuss strategy and divvy assignments, about eight lobbyists from the dissident groups will be missing. They will not be represented on task forces the federation forms to keep up with legislative priorities and will lose access to policy research the federation provides its members.

As a result, Samuel said, the dissident unions will have to ignore certain issues or risk spreading themselves thin trying to keep up.

“If they want to restrict access to us, it seems to me the loss is theirs,” said Mike Mathis, the Teamsters’ political director. “We’ve said from the beginning we want to work with labor, especially on the legislative front. We’ve extended the olive branch. Whether they take it or not is their decision.”

Both Smith and Mathis said their unions have the capability to produce their own research. And with the unions holding steady their spending on lobbying, they said they should have no trouble maintaining their footprint on their range of issues.

Further complicating matters for the breakaway groups, however, the Teamsters and the SEIU find themselves on opposite sides of some high-profile issues.

The Teamsters have aggressively backed attempts by the White House to open the Arctic National Wildlife Refuge to oil drilling, while the SEIU opposed them. The Teamsters and the UFCW supported a guest worker program opposed by the SEIU. And while the SEIU has been a vocal critic of President Bush’s plans to overhaul Social Security, the Teamsters have been largely quiet on the issue.

Mathis said the Change to Win Coalition will only take positions on issues that directly affect the ability of unions to increase their ranks. On anything else, they will simply work together when they agree.

“That’s something the AFL-CIO has had to negotiate, too,” Smith said. “We have a lot of partners and allies we work with on just a few issues where our agenda overlaps. I imagine it will be similar.”

The break could offer Republicans inroads into what has been for decades the near-exclusive provenance of Democrats. Mathis said presidents of the breakaway unions plan to meet with leadership from both parties after the August recess. “As a union, we might do more with the Republicans — if they deserve it,” he said.

Meanwhile, some in the business community, mostly giddy at labor’s rift, see new opportunities to advance an agenda that has already scored several wins this Congress.

“It certainly helps us that they’re in flux right now,” said a source closely affiliated with Compass, the business-backed group pushing to add private accounts to Social Security. “They’re not confident putting money toward ads or viral e-mail campaigns.”

Others are less sure of what the breach means.

Bruce Josten, the top lobbyist for the U.S. Chamber of Commerce, said while labor lobbyists may now amount to a “cacophony of voices, they will still be singing from the same hymn sheet.”

On the other hand, he said, given the heated rhetoric and raw emotions accompanying the rift, “they may be less and less and less inclined to work together.”